Complete the square to solve for $x$. $x^{2}+8x-9 = 0$
Explanation: Begin by moving the constant term to the right side of the equation. $x^2 + 8x = 9$ We complete the square by taking half of the coefficient of our $x$ term, squaring it, and adding it to both sides of the equation. Since the coefficient of our $x$ term is $8$ , half of it would be $4$ , and squaring it gives us ${16}$ $x^2 + 8x { + 16} = 9 { + 16}$ We can now rewrite the left side of the equation as a squared term. $( x + 4 )^2 = 25$ Take the square root of both sides. $x + 4 = \pm5$ Isolate $x$ to find the solution(s). $x = -4\pm5$ So the solutions are: $x = 1 \text{ or } x = -9$ We already found the completed square: $( x + 4 )^2 = 25$